Method and apparatus for the destructive distillation of oil shale



Dec. 28, 1954 2,698,283

D. DALIN METHOD AND APPARATUS FOR THE DESTRUCTIVE DISTILLATION OF OILSHALE Filed June.29, 1950 2 Sheets-Sheet 1 ib' TO 31mm To CONDENSER A.

; -----FEESH me [gas mam-en m2 HEATER PERHEQTER Economzca n\\\\\ y I I P/dtu ew" United States Patent METHOD AND APPARATUS FOR THE DESTRUC- TIVEDISTILLATION OF OIL SHALE David Dalia, Stenkullen, Ronninge,

A/ B Svenska Maskinverken, poration of Sweden Sweden, assignor toSodertalje, Sweden, a cor- This invention relates to the art ofdistilling volatiles from oil-bearing shale and other solid carbonaceousmaterial and has as its purpose to provide an improved method andapparatus therefor.

Many schemes have been proposed in the past for degassing oil shale andthe like and while these various past attempts have met with somemeasure of success, invariably there was always some objection to themethod or the apparatus employed which kept it from being economicallysound.

At the outset, any method for the distillation of oil shale and similarcarbonaceous material to be at all commercially practicable requiresthat it be capable of processing huge quantities of material per unit oftime. This,

Of course, means a continuous process.

Another serious consideration is that the residue coke left after thevolatiles are driven from the material must be disposed of andpreferably its combustible fraction should be burnt to provide the heatneeded in the process.

The present invention fully satisfies these basic requirements and, aswill appear, provides a method and apparatus wherein huge quantities ofcarbonaceous material may be processed per unit of time and whereincombustible fraction of the residue coke is not only burned, but in theburning thereof steam for power production is derived.

In keeping with its general objective of providing a commerciallypracticable and economically sound method and apparatus for thedistillation of oil shale and the like the invention has an another ofits purposes or objects the preheating of the carbonaceous material asit is fed into the distillation zone by the preheated combustion air,the preheating of the combustion air being effected by indirect heatexchange with the flue gases leaving the combustion zone.

Another object of this invention is to utilize the heat contained in theflue gases for driving the volatiles from the carbonaceous material asit moves through a distillation zone, and to this end the inventionprovides for recirculation of the distillation gases sequentially inindirect heat exchange relation with the hot flue gases and then throughthe carbonaceous material in the distillation zone.

Again, with a view toward effecting maximum economy the invention has asanother of its objects the preliminary heating of the raw carbonaceousmaterial directly before it is fed into the preheating zone by passingthe spent, though still hot, flue gases or a part thereof through theraw carbonaceous material before these flue gases move out to the stack.

One of the most serious drawbacks of the methods proposed by othersheretofore for the distillation of volatiles from oil shale and likecarbonaceous material resided in their failure to recognize theimportance of controlling the temperature of the burning residue cokeWhere combustion thereof was employed toprovide the necessary heatsource. Oil-bearing shale and similar carbonaceous material has arelatively low sintering temperature and, therefore, unless thetemperature of the burning material is controlled and excess heatabstracted therefrom the material quickly sinters which, of course, ishighly undesirable. To avoid this objectionable consequence the presentinvention applies the teachings of the Edling et al. Patent No.2,504,508 wherein excess heat is abstracted from the burning fuel bycirculating a suitable cooling fluid, preferably boiler fluid, inindirect heat exchange relation with the burning fuel.

The problem of too high a temperature is, of course,

also encountered in the distillation zone for if the temperature of thematerial therein is permitted to exceed a predetermined safe maximum,the volatiles driven from the 1:{naterial are carbonized and thedistillates begin to crac This invention, therefore, has as another ofits objects to control the temperature of the material undergoingdistillation and accomplishes this purpose by circulating boiler fluidof a temperature correct for distillation in indirect heat exchangerelation with the carbonaceous material being degassed.

With the above and other objects in view, which will appear as thedescription proceeds, this invention resides in the novel method andapparatus hereinafter described and more particularly defined by theappended claims, it being understood that such changes in the preciseembodiment of the hereindisclosed invention may be made as come withinthe scope of the claims.

The accompanying drawings illustrate two complete examples of thephysical embodiment of the invention constructed according to the bestmodes so far devised for the practical application of the principlesthereof, and in which:

Figure 1 is a view diagrammatically illustrating one application of thisinvention and in which the enclosures providing the various zones aswell as the upright passageway down which the column of material beingtreated descends, are shown in section;

Figure 2 is a cross sectional view through Figure 1 on the plane of theline 2-2;

Figure 3 is a view illustrating a slight modification of the apparatus,said view being similar to the main structural portion of Figure 1; and

Figure 4 is a horizontal sectional view through Figure 3 on the plane ofthe line 44.

Referring now particularly to the accompanying drawings, the numeral 5designates a combustion chamber having an air inlet 6 near its bottomand a flue gas outlet 7 near its top from which a flue gas duct 8 leadsto a suction fan 9.

Superimposed upon the combustion zone is a distillation zone 10, apreheating zone 11 and a preliminary heating zone 12. The zones 12 and11 may be said to provide first and second stages of preheating for thecarbonaceous material to be treated which is fed into the top of avertical retort 13 extending through all of the zones. The retort 13also preferably extends across the full width of each zone as shown inFigure 2 so as to divide each zone into an inlet and an outlet chamber.

The lower portion of the retort 13 is defined by relatively closelyspaced vertical boiler fluid containing tubes 14 which constitute partof the steam generating surfaces of a steam boiler deriving its heatfrom the combustion of the residue coke. This steam boiler is'equippedwith a steam drum 15 and is of the forced circulation type, having aforce pump 16 which draws water from the steam drum and forces itthrough the various steam generating tubes, including the tubes 14, andother tubes 17 lining certain of the walls of the combustion chamber.

At its bottom the retort 13 has a grate 18 of any suitable constructionto support the column of carbonaceous material and continually dischargethe ash from the bottom thereof into an ash pit (not shown).

In the distillation zone 10 the retort portion of its length is definedby horizontal boiler fluid containing tubes 19 and has finger-like ductsor tubes 19' to be embedded into the mass in the retort. Superheatedsteam flows to the coils 19 and the ducts or tubes 19' from the outletof a superheater 20 located in the hottest portion of the duct 8 andhaving its inlet connected with the steam drum in the customary manner.The coils 19 and the tubes 19' empty into a header 21 from which thesteam may be led directly to its point of use, or first passed throughanother superheater (not shown) where its temperature and pressure mayhe stepped up.

The retort 13 within the preheating zone 11, for the major portion ofits length, is likewise defined by horizontal boiler fluid containingtubes 22 but these tubes contain hot water or a steam-water emulsionwhich is circulated therethrough by the force pump 16.

In the preliminary heating zone 12 the opposite side 13 for the major-'walls ofthe retort 13, i. e. those also defining one side of the inletand outlet chambers of thezone 12,-areperforate and are preferablydefined by louvers 23.

Those portions of the retort 13 connecting the ad- .jacentzones aredefined byimperforate walls 24, and

26. These imperforate walls facilitate the maintenance of neutral zonesin the retort between the adjacent treat- ;ment zones by which the gasesin one treatment zone are is continuously fed into the top of theupright retort 13 to maintain the height of the column therein. As thisraw carbonaceous material descends through the preliminary heating zone12 it is heated by the passage therethrough of part of the flue gasesflowing to the stack. For this purpose a bypass line 27 connects themain stack line 28 with the inlet chamber 29 of the zone 12 and theoutlet chamber 30 is connected to the stack through a suitable duct line31. Valves 32 and 33 in. the bypass line 27 and the main line 28proportion the volume of the flue gases flowing through the zone 12 andthus provide means for controlling the pressure within this treatmentzone. Obviously the flue gases entering the zone 12 must pass throughthe column of carbonaceaus material to leave the zone and flow on to thestack and in so doing effect a preliminary heating of the rawcarbonaceous material.

Within the preheating zone 11 the carbonaceous material is furtherheated by the passage therethrough of the air for combustion which hasbeen previously preheated. To this end the combustion air which entersthe inlet of a blower 34 is fed through a duct line 35 to an air heater36 located in the flue gas duct 8 where the air is heated. The air thusheated passes through a duct line 37 to the inlet chamber 38 of the zonell. from which it flows through the carbonaceous material under thecontrol of dampers 39 into the outlet chamber 40 of the preheating zone.

From this point part of the combustion air is conducted through a line41 to the combustion air inlet 6 of the combustion zone while theremainder thereof is fed back through a duct line 42 to the inlet of theblower 34-for recirculation. Valves 43 and 44-, in the lines 41 and 42respectively, proportion the amounts of the combustion air fed to thecombustion chamber and recirculated through the air heater.

The hot combustion air flowing through the preheating zone 11 coactswith the hot boiler fluid flowing through the-tubes 22 to effect thedesired preheating of the carbonaceous material.

The carbonaceous material, after being preheated in the mannerdescribcd,passes through the adjacent neutral zone of the retort and into thedistillation zone 19 where the volatile gases are driven off by heatsupplied conjointly by the superheated steam flowing through the tubes19 and 19 and heated distillation gases. To this end the outlet chamber45 of the distillation zone 16 is connected through a duct line 46 withthe inlet of a blower 47 as well as a condenser (not shown) where thegases are condensed and subjected to further treatment.

The blower 47 discharges into a duct line 43 which leads to the inlet ofa gas heater 49 located in the flue gas duct 8 preferably directlydownstream from the superheater 20 and between it and the usualeconomizer 50. The outlet of the gas heater is connected through a ductline 51 with the inlet chamber 52 of the distillationzone 10. Valves 53and 54, located respectively at the inlet of the blower 47 and in theline leading to the condenser, control the proportion of thedistillation gases recirculated through the gas heater and thus enableregulation of the pressure within the zone 10.

The temperature of the superheated steam circulating through the coils19 and the tubes 19 is maintained at the value best suited fordistillation of the carbonaceous material and hence its effect .is tostabilize the temperature of the carbonaceous material undergoingdegassing; abstracting excess heat in the event the distillation gasesentering the zone 10 from the heater 49 are :too hot and imparting heatif the temperature of these tained in 'the'distillation zone.

The degassed residue coke passes through the adjacent neutral zone intothe combustion zone where it is burned, the air for combustion beingsupplied thereto in the manner described and being distributed over thefull height of the fuel bed in accordance with the setting of dampers55. i

It is to be noted that the incoming combustion air which enters thecombustion zone at its bottom first flows transversely through theextreme lower portion of the retort and then passes transversely acrosstherethrough at different levels in accordance with the setting of'thedampers 55. All of the material being burned in the combustion zone isthus fed the proper volume of combustion air and, as will be readilyapparent, the total volume of air fed to the combustion chamber may beregulated to produce an optimum rate of combustion.

This latter desirable result is enabled by the fact that the temperatureof the burning mass is controlled to preclude sintering thereof and incertain cases the dissociation of mineral CO2 by the circulation ofboiler fluid through the finger-like ducts or tubes 56- imbedded in theburning mass and connected in the steam generating system of the boilerto have boiler fluid continuously circulated therethrough. Thus theboiler fluid circulated through the tubes 56 coacts withthe boiler fluidflowing in the tubes 14 to effectively abstract the excess heat from theburning mass and thereby enable rapid combustion of the combustiblefraction residue coke without the danger of sintering and in certaincases the dissociation of mineral C02.

The heat obtained from the burning of the coke residue is suflicient forordinary requirements. To take care of abnormal demands upon the boiler,a gas or oilburner 57 mounted in a wall of the combustion chamber,provides a supplemental heat source.

Since the volumeof material that can be combusted per unit of timelargely determines the capacity ofthe plant and since the material beinghandled burns notoriously slow, it may be desirable to increase thecross sectional dimensions of the lower portion of the retort andconsequently the overall volume of the material being combusted. Thismay be done in the manner shown in Figure 3'Wh616l1'1 the sides of thelower'retort portion defined by the coils '14 are spaced farther apartand the coils 56 imbedded in the burning mass are -increased in numberto enable the cooling effect of the boiler fluid flowing therethrough toreach ail portions of the burning fuel. Such increase in the horizontalarea of the burning fuel bed also has the desirable advantage ofenabling reduction in the overall height of the unit.

From the foregoing description taken in connection with the accompanyingdrawings, it will be readily apparent to those skilledinthe art thatthis invention provides a practical and economically sound method ofdistilling the volatiles from oil-bearing shale and similar carbonaceousmaterial and that the invention lends itself to practice by means ofrelatively simple apparatus.

What I claim as my invention is:

1. Apparatus for distilling oil-bearing shale and similar solidcarbonaceous material, comprising: means defining a retort dividedvertically into a preliminary heating zone, a-preheating zone below thepreliminary heating zone, a distillation zone below the preheating zone,and a combustion zone below the distillation zone, said zones being inopen communication with one another so that carbonaceous material fedinto the top of the retort can pass from each zone directly intothe'next zone therebelow; a flue gas duct-leading from the combustionzone; a primary heat exchanger in the flue gas duct in which heatexchangefluid may be-heated by indirect heat exchange with the hot fluegases to a temperature at least as high as that at which distillation ofthe carbonaceous material takes place; a secondary heat exchanger in thedlstillation zone connected with said primary heat exchanger to enableheated heat exchange fluid'to impart its heat to the carbonaceousmaterial by indirect heat exchange to effect distillation thereof; anair preheatcr in the flue gas duct downstream from said primary heatexchanger; means for passing preheated air from said airpreheaterthrough the carbonaceous material in the preheating zone topreheat the same by direct heat ex-- heating zone to the combustion zoneto take part in the combustion process; means connecting said flue gasduct, at a location downstream frrm said air preheater, with saidpreliminary heating zone, and for passing flue gas across thecarbonaceous material in said preliminary heating zone in direct heatexchange relation therewith; and means for regulating the relativepressures of the air and flue gases passing through the carbonaceousmaterial and the distillation gases in the distillation zone to maintainsaid pressures at values such as to preclude the admixture of flue gasesin the preliminary heating zone with distillate products in thedistillation zone.

2. The apparatus of claim 1, further characterized by means forrecirculating a portion of the air which has been passed through thecarbonaceous material in the preheating zone through the air preheater.

3. Apparatus for distilling oil-bearing shale and similar solidcarbonaceous material, comprising: means defining a retort dividedvertically into a preliminary heating zone, a preheating zone below thepreliminary heating zone, a distillation zone below the preheating zone,and a combustion zone below the distillation zone, said zones being inopen communication with one another so that carbonaceous material fedinto the top of the retort can pass from each zone directly into thenext zone therebelow; a flue gas duct leading from the combustion zone;means for etfecting indirect heat exchange between flue gases from thecombustion zone and carbonaceous material in the distillation zone; anair preheater in the flue gas duct; means for passing preheated air fromsaid air preheater through the carbonaceous material in the preheatingzone to preheat the same by direct heat exchange therewith; means forconducting air which has been passed through the carbonaceous materialin the preheating zone to the combustion zone to take part in thecombustion process; means connecting said flue gas duct, at a locationdownstream from said air preheater, with said perliminary heating zone,and for passing flue gas across the carbonaceous material in saidpreliminary heating zone in direct heat exchange relation therewith; andmeans for regulating the relative pressures of the air and flue gasespassing through the carbonaceous material and the distillation gases inthe distillation zone to maintain said pressures at values such as topreclude the admixture of flue gases in the preliminary heating zonewith distillate products in the distillation zone.

4. The method of distilling oil-bearing shale and similar solidcarbonaceous materials which comprises: moving the carbonaceous materialin a column through a preliminary heating zone and downward successivelythrough a preheating zone, a distillation zone and a combustion zoneWhere the degassed material is burned; passing flue gases from thecombustion zone in heat exchange relation with a heat exchange medium;heating carbonaceous material in the distillation zone to distillationtemperatures by passing said material in heat exchange relation withsaid heat exchange medium; heating combustion air by passing the same inindirect heat exchange relation with the flue gases which have beenpassed in indirect heat exchange relation with said fluid heat exchangemedium; passing the heated combustion air through the column ofcarbonaceous material in the preheating zone, in direct heat exchangerelation therewith; thereafter conducting said air to the combustionzone to maintain combustion; passing flue gases which have heated saidcombustion air through the column of carbonaceous material in thepreliminary heating zone, in direct heat exchange relation therewith;and regulating the relative pressures of the air in the combustion zone,the distillation gases in the distillation zone and the flue gases inthe preliminary heating zone to maintain the same at a value which willpreclude intermingling of the flue gases in the preliminary heating zonewith distillate products in the distillation zone.

5. The method of claim 4 further characterized by the step ofrecirculating a portion of the combustion air which has been passedthrough the column of carbonaceous material in the preheating zone inindirect heat exchange relation with flue gases to reheat said air.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,805,109 Runge et al. May 12, 1931 1,866,399 De Baufre July5, 1932 2,131,702 Berry Sept. 27, 1938 2,383,636 Wurth Aug. 28, 19452,445,327 Keith July 20, 1948 2,448,223 Lantz Aug. 31, 1948 2,504,508Edling Apr. 18, 1950 2,550,677 Dalin et al. May 1, 1951 FOREIGN PATENTSNumber Country Date 283,259 Great Britain Jan. 2, 1928 107,907 AustraliaJuly 5, 1939

1. APPARATUS FOR DISTILLING OIL-BEARING SHALE AND SIMILAR SOLIDCARBONACEOUS MATERIAL, COMPRISING: MEANS DEFINING A RETORT DIVIDEDVERTICALLY INTO A PRELIMINARY HEATING ZONE, A PREHEATING ZONE BELOW THEPRELIMINARY HEATING ZONE, A DISTILLATION ZONE BELOW THE PREHEATING ZONE,AND A COMBUSTION ZONE BELOW THE DISTILLATION ZONE, SAID ZONES BEING INOPEN COMMUNICATION WITH ONE ANOTHER SO THAT CARBONACEOUS MATERIAL FEDINTO THE TOP OF THE RETORT CAN PASS FROM EACH ZONE DIRECTLY INTO THENEXT ZOEN THEREBELOW; A FLUE GAS DUCT LEADING FROM THE COMBUSTION ZONE;A PRIMARY HEAT EXCHANGER IN THE FLUE GAS DUCT IN WHICH HEAT EXCHANGEFLUID MAY BE HEATED BY INDIRECT HEAT EXCHANGE WITH THE HOT FLUE GASES TOA TEMPERATURE AT LEAST AS HIGH AS THAT AT WHICH DISTILLATION OF THECARBONACEOUS MATERIAL TAKES PLACE; A SECONDARY HEAT EXCHANGER IN THEDISTILLATION ZONE CONNECTED WITH SAID PRIMARY HEAT EXCHANGER TO ENABLEHEATED HEAT EXCHANGE FLUID TO IMPART ITS HEAT TO THE CARBONACEOUSMATERIAL BY INDIRECT HEAT EXCHANGE TO EFFECT DISTILLATION THEREOF: ANAIR PREHEATER IN THE FLUE GAS DUCT DOWNSTREAM FROM SAID PRIMARY HEATEXCHANGER; MEANS FOR PASSING PREHEATED AIR FROM SAID AIR PREHEATERTHROUGH THE CARBONACEOUS MATERIAL IN THE PREHEATING ZONE TO PREHEAT THESAME BY DIRECT HEAT EXCHANGE THEREWITH; MEANS FOR CONDUCTING AIR WHICHHAS BEEN PASSED THROUGH THE CARBONACEOUS MATERIAL IN THE PREHEATING ZONETO THE COMBUSTION ZONE TO TAKE PART IN THE COMBUSTION PROCESS; MEANSCONNECTING SAID FLUE GAS DUCT, AT A LOCATION DOWNSTREAM FROM SAID AIRPREHEATER, WITH SAID PRELIMINARY HEATING ZONE, AND FOR PASSING FLUE GASACROSS THE CARBONACEOUS MATERIAL IN SAID PRELIMINARY HEATING ZONE INDIRECT HEAT EXCHANGE RELATION THEREWITH; AND MEANS FOR REGULATING THERELATIVE PRESSURES OF THE AIR AND FLUE GASES PASSING THROUGH THECARBONACEOUS MATERIAL AND THE DISTILLATION GASES IN THE DISTILLATIONZONE TO MAINTAIN SAID PRESSURES AT VALUES SUCH AS TO PRECLUDE THEADMIXTURE OF FLUE GASES IN THE PRELIMINARY HEATING ZONE WITH DISTILLATEPRODUCTS IN THE DISTILLATION ZONE.